666642856324 has 9 divisors (see below), whose sum is σ = 1166627856261. Its totient is φ = 333320611680.

The previous prime is 666642856307. The next prime is 666642856331. The reversal of 666642856324 is 423658246666.

The square root of 666642856324 is 816482.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 26770849924 + 639872006400 = 163618^2 + 799920^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1428844 + ... + 1837084.

Almost surely, 2^666642856324 is an apocalyptic number.

666642856324 is the 816482-nd square number.

It is an amenable number.

666642856324 is a deficient number, since it is larger than the sum of its proper divisors (499984999937).

666642856324 is an frugal number, since it uses more digits than its factorization.

666642856324 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816486 (or 408243 counting only the distinct ones).

The product of its digits is 59719680, while the sum is 58.

The spelling of 666642856324 in words is "six hundred sixty-six billion, six hundred forty-two million, eight hundred fifty-six thousand, three hundred twenty-four".